Lyrics:

The Song:

In order for it to feel more authentic, Beck filled out his Song Reader book with fragments of songs and melodies, as well as fictional album collections and song titles. "Giddy Up! Giddy Up! We're On Our Way To War" is listed as part of a series of "Late Patriotic Song Successes," all songs about soldiers and war and the like (a popular genre of sheet music in the early 1900s).

The idea of "Late Patriotic Song Successes" came from a piece of sheet music that you can see here. Many of Beck's patriotic titles come from this page, which includes a song entitled "Giddy Giddap! Go On! Go On! We're On Our Way To War."

Beck's short fragment though seems to be entirely original in lyric and melody, it's just the title that he adapted.

Also, Beck's song is credited to "Gideon Shaffner," which as far as I can tell is just a made-up pseudonym.